Add command description support for the SHELL_CMD

[vpetrigo]

Hello,

I would like to propose a change in the SHELL_CMD structure that allows a user to provide theirs own command description that may be used in the help command for example:

• Proposed changes:

typedef struct shell_cmd {
    const CPU_CHAR *Name; ///< Ptr to cmd name.
    SHELL_CMD_FNCT Fnct;   ///< Ptr to cmd fnct.
    const CPU_CHAR *Descr; ///< Ptr to cmd description.
}

• Outcome for the help command (implementation specific):

help: Print commands info
status: Print system status
reboot: Perform software reboot
bootloader: Switch into the bootloader application

[forg0ne]

Thank you for the suggestion.
We may decide to add this change at a later date.
However, for the time being we recommend placing the text in the help command itself.